The present invention relates to process variable transmitters of the type used in industrial process control and monitoring systems. More specifically, the present invention relates to the compensation of a sensed process variable in a process variable transmitter.
Process variable transmitters are used to monitor industrial processes such as oil refineries, paper pulp manufacturing, etc. The process variable transmitter measures a process variable such as pressure, temperature, flow rate, level, etc. of a process fluid. The measured process variable can be transmitted to another location such as a centralized process control room. The transmission can be over a wired connection such as a two wire process control loop, or it can be over a wireless connection. The sensed process variable may be used to monitor the process, or may be used to control operation of the process.
The process variable is measured using a process variable sensor. Typically, the process variable sensor does not provide a direct linear relationship between its output and the process variable being sensed. The output may be non-linear as a function of the measured process variable, or as a function of other parameters such as temperature of the process variable sensor, etc. It is therefore desirable to compensate the measured process variable in order to improve accuracy of the measurement.